West Texas Intermediate (WTI) crude oil has slumped close to 20 per cent since June this year to $US83.18 per barrel, while Brent crude oil has spiralled more than 23 per cent lower to $US86.46 per barrel.

Many OPEC members, led by Saudi Arabia, refuse to curtail production for fear of losing market share to the growing US shale liquids industry.

"In the face of falling global and US crude oil prices, a key question becomes: how low would WTI prices have to go to meaningfully slow down US shale production growth?" Citi analyst Eric Lee said.

WTI oil prices at $US70 per barrel could begin to reduce new well production in the US, by up to 30 per cent if costs are at the high end of estimates, but by close to zero if costs are at the low end of estimates, Mr Lee said.

"To bring US shale production growth to zero – that is, to reduce new-well production to only just cover legacy well declines – might need prices ranging from $US40-60 per barrel," Mr Lee said.

There is a diverse range of breakeven prices across the US shale industry, even if fringe production output is cut, productivity gains could offset any price support.

"A 40 per cent reduction in rigs or more might be needed to completely flatten production growth but this is based on modelled reductions of average wells, not the least productive wells. Productivity gains can also offset this further. In any case, at $US70 WTI, this is a slowdown, not a halt, in production growth," Mr Lee said.

International Energy Agency executive director Maria van der Hoeven estimated 98 per cent of oil and condensates produced in the US had a breakeven price of less than $US80 a barrel, and 82 per cent has a breakeven price of $US60 or lower.

CLSA head of Asian oil and gas Simon Powell said that the recent correction in oil prices wasn't only related to North American liquid production.

Rather it was driven by a culmination of factors which also included extra production in the Middle East, Libya returning to the market and Iraq producing despite the insurgence threat there, as well as easing Asian demand creating a supply glut.

"The world is in oversupply right now. But, [northern hemisphere] winter is just around the corner. "

The Saudis and the rest of OPEC are likely to signal production cuts prior to their next meeting in late November, Mr Powell said.

"The Saudis saying that they wouldn't cut was just sending a message to the rest of OPEC saying 'why should we be the only ones who have to cut?'."

The market is also wrongly assuming that US shale production can "continue into the stratosphere" Mr Powell said.

"Production costs for shale liquids in America will rise because the nice and easy stuff has been got at. It'll still be good, but I think the rate of liquid production growth in the US will slow."